Establish the uSI Values and End-user Training Material That Will be Used to Guide Oxytocin Dosing Actions

Background. Oxytocin stimulates the uterus, increases the strength and frequency of uterine contractions and facilitates delivery. The "dose" of oxytocin is the rate of IV infusion. In a typical labor where oxytocin is used, many dosing adjustments are performed over many hours. Finding the correct dose for a given patient is challenging because some women respond rapidly to low doses of oxytocin, others require high doses. The correct dose is important because the risks of adverse outcomes increase when doses are either too low or excessive. The dosing actions increase, hold, decrease or stop are typically performed every 30 minutes during oxytocin administration.

Dosing actions are performed based on the current level of simulation caused by the current dose. To assess the level of stimulation, current methods rely heavily on the output of the fetal monitor, which produces contraction frequency and fetal heart rate. Additional information for dosing decisions is obtained from subjective assessments such uterine palpation. Subjective measures are used because there is no objective method available to reliably guide a dosing action. Subjectivity is a major contributor to the long duration of labor for inductions and the high rate of excessive uterine stimulation with any oxytocin use.

The uterine stimulation index (uSI) is an objective measure of the current level of stimulation caused by the current dose of oxytocin in individual patients and can be used to guide oxytocin dosing actions. uSI is based on an electromyography (EMG) signal that is proportional to the effects of oxytocin on the uterine muscle. uSI is calculated from multichannel EMG to obtain a representative sampling of the effects of oxytocin on entire uterus. The range of values for uSI is from 0 (no oxytocin effects) to 10 (maximal oxytocin effects). Low values of uSI guide the end-user to increase the current dose of oxytocin. Intermediate values of uSI guide the end-user to hold the current dose. High values of uSI guide the end-user to decrease the current dose.

The purpose of this study is to establish the ranges of uSI values that correspond to the dosing actions increase, hold and decrease. To establish these ranges, 51 subjects will undergo current methods of dosing while having multichannel EMG recorded. uSI values will not be available to end-users, so all subjects will receive dosing actions determined by standard of care using current method. After delivery, a panel of experts will retrospectively assess each dosing action based on the outcome of the dosing action. These "optimized dosing actions" will then be correlated with the uSI value obtained at that time. This process produces paired data of optimized actions and uSI values. From the clustering of the uSI values, the ranges of uSI can be matched to the dosing actions increase, hold and decrease.

As a second goal, human factors will be studied with questionnaires and end-user interviews to improve the methods used for recording multichannel EMG during labor.